Scooby-Doo and the Return of Anthos the Warlock! (1979)

When the gang are at a visit at a mansion with Harlem Globetrotters, Fat Albert and the Cosby Kids, and Blue Falcon and Dynomutt, Anthos the Warlock has returned, and has transformed the Harlem Globetrotters into one black pixie, and Velma into an aged skeleton, and now Scooby, Shaggy, Blue Falcon, Dynomutt, Fat Albert and the Cosby Kids have to put an end to Anthos.